1. Field of Invention
This invention prevents grass or weed growth around the base of an expanding tree or shrub via a series of overlapping, semi-circular wings.
2. Prior Art
The problem of enhancing tree growth while simultaneously curtailing grass or weed growth has been addressed in the prior art. However, the emphasis on weed control has often been at the expense of trunk expansion. For example, U.S. Pat. No. 5,396,731 to Byrne (1995) discloses a porous, preformed mulch pad with a central aperture and lockable slit. The design inherent to U.S. Pat. No. 5,396,731 could mean that as the trunk expands, the central opening of the pad could be destroyed, thus compromising the stability of the design. U.S. Pat. No. 4,268,992 to Scharf, Sr. (1981) encounters a problem similar to that of U.S. Pat. No. 5,396,731. In U.S. Pat. No. 4,268,992, damage to the tree protector caused by an expanding tree trunk is not addressed as the tree is enclosed by a hollow vertical shaft. Instead, the focus of U.S. Pat. No. 5,396,731 is the built-in water system to channel water into the subsoil. U.S. Pat. No. 3,305,969 to Mattson (1967) discloses a tree or plant protector collar, which is a prefabricated, one-piece mulching pad with a non-expandable collar and a slit from inner to outer periphery. A thin, conical weed control plate with a slit from outer to inner periphery was disclosed in U.S. Pat. No. 6,276,869 to Yakushinji (2001). As U.S. Pat. No. 6,276,869 is of solid material, held along one edge by nuts and bolts, it is not cutable to allow for an expanding trunk diameter.
To account for an expanding trunk, U.S. Pat. No. 6,705,044 to Clancey (2004) discloses an adjustable root cover which is essentially an ergonomic pad of varying shapes, made of flat, woven cloth. According to trunk size, two cords located along the inner periphery tighten the cover in opposite directions but entail refitting as the trunk expands. Another weakness of the design is that a slit extends from inner to outer periphery, inducing grass or weed growth.
Another approach was proposed by U.S. Pat. No. 5,085,001 to Crawley (1992) in which a stabilized mulch skirt with a plurality of adjustment strips may allow a customized fitting of the skirt around the trunk's diameter. There are three potential weakness in U.S. Pat. No. 5,085,001 as it is made of flexible material, has serrations to form concentric circles, as well as a slit from inner to outer periphery, all of which may breakdown and allow growth of grass or weeds. Another landscaping cover of flexible material was disclosed in U.S. Pat. No. 5,522,176 to Suttle (1996). In U.S. Pat. No. 5,522,176, concentric circular paths are defined on the material and can be cut according to size of the trunk's diameter. As with U.S. Pat. No. 5,085,001, the flexible material and slit from inner to outer periphery described in U.S. Pat. No. 5,522,176 can be broken down by studier grass or weeds. U.S. Pat. No. 5,323,557 to Sonntag (1994) discloses a landscaping mat with a flexible inner portion. As the trunk's diameter expands, the design of U.S. Pat. No. 5,323,557 can be expanded by cutting along the concentrically scored lines. Still, U.S. Pat. No. 5,323,557 faces the problem of grass or weed growth along a slit from inner to outer periphery. Another design, U.S. Pat. No. 4,308,688 to Revane (1982) discloses a tree well cover composed of two or more preformed fiberglass sections. Along the base of the design used in U.S. Pat. No. 4,308,688, concentric rings can be cut to allow for the growing tree trunk, but also faces the problem of grass or weed growth along the slits.
U.S. Pat. No. 4,648,203 to Worzek (1987) discloses a tree protector consisting of a plurality of crescent shaped flaps, hinged to each other on each side of the centerlines. The design allows for an expansion of the trunk yet also allows grass or weed growth along the centerlines where light permeates. Moreover, studier grasses or weeds can uplift one or more sides of the crescent shaped flaps, even before contact with the trunk and hereby rendering this feature useless. Finally, in the case of a non-cylindrical trunk, e.g. the formation of buttress roots, U.S. Pat. No. 4,648,203 would be uplifted unevenly, allowing undue grass or weed growth.
The design of the present invention addresses many of the problems encountered in the prior art. For example, the present invention with its series of overlapping, semi-circular wings can expand according to either a cylindrical or non-cylindrical tree trunk. As the individual wings are in close contact with the trunk, and rely on pressure from the expanding trunk diameter to move outward, grass or weeds are prevented from permeating the base. In addition, the design of the present invention allows the overlapping wings to mutually apply pressure to hold the adjacent wings downward, thus applying opposite force to upward-pressing grass or weeds. Finally, the overlapping, semi-circular wings close and cover the slit used for opening and mounting the present invention around a tree trunk, thereby eliminating the slit as a location for grass or weed growth.